Carburetor



April 20, 1954 E. M. BIMBERG 2,676,004

CARBURETOR Filed March 30, 1949 7676 [Z I 2; I I: 64 F L 45 74 I I 3 X 72 M I 0 44 42 66 M I M I ll 7/22 '40 INVENTOR. gym? M. B/MBEEG ATTORNEY Patented Apr. 20, 1954 UNITED STATES PATENT OFFICE CARBURETOR Elmer M. Bimberg, Detroit, ."Michi, assignor vato Bendix Aviation Corporation, sont-h-Bend lndn a corporationofDelaware Application March 30, 1949, Serial No."84,44'6

"4 Claims. .1

'fI'he present invention relates to carburetors for internal combustion engines and the like, and more particularly to an .improved idle systemitorsaidcarburetors.

In. many commercial carburetors for internal combustion engines, the fuel for engine idling is taken from the main discharge system and mixed "with air usually supplied from the air horn, to form an emulsion which is then discharged :into the induction passage on the enginezsideoffithexthrottle valve. Undersome conditions of operation, such as during high speed or hlgh power output, the fuel and airflow in certain portions-of the idling system reverse direction, permitting -the-air for idling to bleed into the. main discharge system, thus leaning out the f-uel-air mixture supplied to the engine at a time when a, somewhat richer mixture is required. This reversal of flow in the idle system ls caused by the high suction in the main discharge -jet at. a time when there is substantially no-:suotion=on the discharge ports of the idle system. "'It is, therefore, one of the principal objects of 'the present invention to provide an air supply means for the idling system which will minimize-or completely prevent the reverse flow of air lin the idle system. Further objects and advantages of the present invention will become apparent from the following description and ac.- companyingidrawing, wherein:

Figure 1 is a vertical cross-sectional view through the carburetor in which the idling system has beenrearranged to more clearly show its relationship to the main discharge, jet; and

Figure -2'is a top plan view of the main body of -the carburetor taken on line 22 of Figure 1.

.Refferringmore specifically to thedra-wing and toFigure l, in particular, there is shown a conventional downdraft single barrel carburetor for an internal combustion engine wherein numeral lll ..designates the main body,.l2 an air horn, Ila, throttle body, and iii a fuel bowl or float chamber having a float I8 mounted therein for controlling ,9, conventional fuel inlet valve (.not shown). The throttle body [4 is secured to the intake manifold of the engine by suitable bolts extending through flange 20 and contains a throttle valve 22 mounted on throttle shaft 24 which is actuated by any conventional throttle operating means such as accelerating pedal.

The main body 10 contains a large venturi 30. small venturi 32 concentrically located in respect to the large venturi, and a fuel discharge system 34 connecting the fuel bowl I 6 With the throat of the small venturi. The small venturi is held '2 in'place by oppositely disposed fins 36 'and 38 which are preferably cast integrally with said ventu-ri and held in place in the main body by oppositely disposed recesses in the side wall thereof.

The main fuel metering system '34 includes a main fuel well All connected near theilower end thereof with the fuel bowl through conduit :42,

metering orifice '44 in conduit 42, and port 46.

in the bottom of the fuel bowl, and connected near the upper end thereof with'the throat of the small venturi through conduit 48 and discharge nozzle 19. Disposed in well 40 and extending from the top thereof to .a short distance from the bottom, is a sleeve member 50 having several vertical rows of ports "52 for admittinginto the well the 'airdelivered from the air horn through conduit 54, annular space 55, ports '58 to the internal portion of sleeve member 50. The

' air entering well 49 through ports 52 mixes withthe fuel in said well to form a 'f-uel-airemu'lsion which is discharged through conduit 48 and nozzle- 49 into the throat of the small venturi.

"The idle system receives its fuel from the main discharge jet through port 59 in the bottom or sleeve member 50 and tube -50 extending throughout substantially the entire length of said'sleeve member and having a small orifice 61 in the upper end thereof for metering the fuel for idling. As the fuelpasses through the idle system, it is mixed with air admitted :through conduit '62 at junction 64 to form a fuel-air emulsion which is discharged through the idle discharge port 65 adjacen'tthe upper edge of the throttle valve.

In conventional carburetors of similar construction, the air supplied to the idle system is delivered directly from the air horn. As the speed of the engine increases, the suction on'the main discharge system in the throat of the small venturi sometimes becomes sufliciently great to 5 cause the airflow through the idling system in the reverse direction, entering the main fuel dis- I charge system, as 'for example in the presentcarburetor, through tube ii-ll, port 59 and Well 40, undul leaning out the fuel-air mixture of the main fuel supply; In the present invention,

the main discharge system remains substantially constant regardless of air flow in the induction passage or suction on the nozzle of the main discharge jet. As shown in Figure 1, air supply conduit 62 of the idling system is connected with the throat of the small venturi through conduits and 72 and nozzle 13. A fixed restriction I4 and a variable restriction 16 controlled by adjustable valve 78 are provided in the idling air supply conduits in order to obtain the proper amount of air for the idle system under various operating conditions.

The carburetor embodying the present invention also includes the usual additional elements found in conventional automotive internal combustion engine carburetors such as accelerating pump, power enrichment jet and choke valve.

In the operation of the present carburetor, starting with the throttle valve in closed or in substantially closed position as shown in Figure 1, the fuel for idling flows from well 40 through tube 60, metering orifice 6|, thence passes to conduit junction 54 Where it mixes with air admitted through conduits 12, 10 and 62 and variable restriction 16 to form a fuel-air emulsion which is discharged through orifice 66 into the induction passage adjacent the throttle valve. As the throttle valve is opened, the fuel is supplied to the induction passage by the main discharge system 34 through port 68, main metering orifice 44, conduit 42, well 40 where it mixes with air supplied through conduit 54, ports 58, sleeve 50 and ports 52 to form a fuel-air emulsion which is discharged through the main discharge conduit 48 and nozzle 49 into the throat of the small venturi. As the throttle valve is opened further and the speed of the engine and the air flow through the carburetor increases, the suction on the main discharge jet also increases. In the carburetor embodying my invention, however, there is no substantial increase in the tendency of the air to reverse its flow through the idle system and flow into the main discharge system since they suction in the small venturi on nozzle 13 of the idle air bleed increases correspondingly to that on nozzle 42 of the main discharge system, so that the efiect of the suction in the main system transmitted to the idling system is balanced by the suction transmitted from the small venturi through conduits i2, 10 and 62.

Although only one embodiment of my invention has been shown and described herein, it is understood that many modifications may be made to suit requirements.

I claim:

1. In a carburetor having an induction passage, a throttle valve, a venturi, and a main discharge system communicating with said venturi and having a metering restriction constituting the last substantial restriction therein: an idle system comprising a fuel conduit communicating with the main discharge system posterior to said metering restriction and with the induction passage posterior to said throttle valve, and a passageway forming substantially the sole air supply means for said idle system communicating with said fuel conduit and with said venturi on the same transverse plane as and in spaced relation to said main discharge system.

2. In a carburetor having an induction passage, a throttle valve, a venturi, and a main discharge system communicating with said venturi: an idle system comprising a fuel conduit communicating with the main discharge system posterior to any substantial restriction therein and with the induction passage adjacent the throttle valve, and a passageway communicating with said fuel conduit and with said venturi on the same transverse plane as and in spaced relation to said main discharge system.

3. In a carburetor having an induction passage, and a main discharge system connected to said induction passage and having a metering restriction constituting the last substantial restriction therein: an idle system comprising a fuel conduit communicating with the main discharge system posterior to said metering restriction and with the induction passageposterior to the point at which the said main discharge system is connected thereto, and a passageway forming the sole air supply means for said idle system communicating with said fuel conduit and with said induction passage on the same transverse plane as and in spaced relation to said main discharge system, said passageway and said main discharge system being so located relative to each other that substantially the same pressure is maintained therein throughout the operating range of the carburetor.

4. In a carburetor having anzinduction passage, a throttle valve, and a main discharge sys tem connected to said induction passage on the air intake side of said throttle valve and having a metering restriction constituting the last substantial restriction therein: an idle system comprising a fuel conduit communicating withthemain discharge system posterior to said metering restriction and with the induction passage posterior to said throttle valve, and a passagewayforming the sole air supply means for said idle system communicating with said fuelconduit andwith said induction passage on the same transverse plane as and in spaced relation to said main discharge system, said passageway and said main discharge system being so located relative to eachother that substantially the same pressure is maintained therein throughout the operatingrange of the carburetor.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,416,858 Mock May 23, 1922 1,452,451 Webber Apr. 17,1923 1,716,619 Chase June 11, 1929 1,767,664 Geiger June 24, 1930 1,865,851 Geiger July 5, 1932 1,929,266 Viel Oct. 3, 1933 1,934,130 Kirby Nov. 7, 1933 1,958,542 Kirby May 15, 1934 2,035,681 Udale Mar. 31, 1936 2,406,114 Sloane et al Aug. 20, 1946 2,512,085 Boller June 20,1950 

